Answer:

Allaah the most high says:  كَلَّا بَلْ رَانَ عَلَى قُلُوبِهِم مَّا كَانُوا يَكْسِبُونَ

[”Nay! But on their hearts is the Ran (covering of sins and evil deeds) which they used to earn.’’ [83:14]   Shaykhul Islaam Ibn Taymiyyah (rahimahullaah) derived from this ayah that sin is a cause of not (being able) to understand the Qur’aan.

[source: Shaykh Ibn Utheymeen –Fawaa’id wa musaabaqaat al ma’een min fataawaa wa duroos Ibn Utheymeen – P.142]

Translated by: Abu Zainab Muhammad Al-Hindee